This invention relates to an improved electrical musical instrument for automatically producing a sequential series of related tones.
Electronic organs have included circuitry for producing a sequential series of related tones. Such special effects are generally provided only on electronic organs having a lower or accompaniment keyboard manual and an upper or melody keyboard manual. In particular, the execution of an arpeggio, a glissando or a strum musical effect either requires an accomplished organist or automatic circuitry which allows an amateur to accomplish these special musical effects.
Prior electronic organ circuits for automatically producing an arpeggio effect, typically consist of a plurality of gates which are sequentially enabled by an analog circuit to pass tone signals, when present at the gate, to a keyer in order to produce a corresponding audible tone. The arpeggio effect is produced by depressing selected keys of the lower manual, and then actuating an arpeggio switch. The analog circuit then generates a ramp voltage which sequentially enables the gates to cause sequential sounding of the selected tones in the same octave as selected on the keyboard, followed by sequential enabling of the same tones in the next octave, followed by the following octave, until all octaves of the organ have been enabled. The effect is similar to an accomplished organist depressing selected keys of the lower manual, while simultaneously sequentially depressing the same key of the same octave on the upper manual, followed by the sequential depressing of the same keys but in the next octave of the upper manual, and so forth. An example of such a circuit is shown in U.S. Pat. No. 3,617,602 to Kniepkamp.
An automatic glissando is somewhat similar to an automatic arpeggio, except that all notes of each octave are enabled. The effect is that of a skilled organist sequentially playing all notes of the upper manual, from the lowest note to the highest note. If the organ were in a sustain mode, the sequentially enabled notes would be slurred together, producing the effect of a glide rather than a glissando. Heretofore, such an effect could be produced in an automatic arpeggio organ by depressing all keys in an octave, and then actuating the automatic arpeggio switch. The result would be a glissando effect, starting with the lowest frequency note which had been depressed.
A strum effect is produced by the sequentially enabling of a related series of notes in one octave, and repeating the sequential enabling after the lapse of a period of time. The resulting effect simulates the strumming of a guitar. Such an automatic strumming circuit has been provided by an analog switching circuit which has a capacitor for integrating a voltage to initiate a delay interval. An example of such a circuit is shown in U.S. Pat. No. 3,235,648 to George.
Various problems have been encountered with prior circuits for automatic sequential enabling of tones. When many octaves are to be played, the analog ramp for controlling sequential enabling of gates must be very precise, requiring components of extremely limited tolerance. The complexity of prior circuits has not made it possible to combine various sequential musical effects, to provide a single circuit which will produce both a strum and an arpeggio and/or glissando. Another serious problem is that the note interval generally must be the same as the sequential switching interval, producing an unrealistic sound which does not properly simulate the musical effect which is produced by a skilled organist. This problem has been compounded by the necessity for simultaneously actuating several organ controls in order to produce the desired musical effect, which operation is difficult for an amateur organist who desires to be able to simulate a more realistic musical effect.